Oil well logging has been known for many years and provides an oil and gas well driller with information about the particular earth formation being drilled. Hydrocarbons are generally contained in reservoirs formed in rock formations with various lithologies. The type of lithology may provide information as to the size and location of hydrocarbon containing reservoirs. Information regarding the type of lithology encountered during exploration and production may provide indications of the location and extent of hydrocarbons in a given earth formation.
Studies of the earth formations indicate the regular occurrence of naturally radioactive elements in various proportions depending on the type of lithology. Commonly, radioactive isotopes of potassium, uranium, and thorium are found in earth formations. Additional radioactive isotopes may be generated in hydrocarbon bearing lithologies during nuclear logging. A rigid or non-rigid carrier is often used to convey the nuclear radiation detectors, often as part of a tool or a set of tools, and the carrier may also provide communication channels for sending information up to the surface.